Angiotensin II induces phosphorylation of glucose-regulated protein-75 in WB rat liver cells

Studies in vascular smooth muscle cells suggest that, angiotensin II (Ang II)-mediated cellular response requires transactivation of epidermal growth factor receptor (EGF-R), and involves tyrosine phosphorylation of caveolin-1. Here we demonstrate that, exposure of WB rat liver cells to Ang II does...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics 2007-01, Vol.457 (1), p.16-28
Main Authors: Krishna, Sharath B., Alfonso, Lloyd F., Thekkumkara, Thomas J., Abbruscato, Thomas J., Jayarama Bhat, G.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino Acids - metabolism
Angiotensin II
Angiotensin II - pharmacology
Angiotensin II - physiology
Animals
Caveolin 1 - metabolism
Cell Line
Chaperone
Cytoplasm - metabolism
EGF-R transactivation
Enzyme Activation
Extracellular Signal-Regulated MAP Kinases - metabolism
GRP-75
HSP70 Heat-Shock Proteins - metabolism
Liver - cytology
Membrane Proteins - metabolism
Mitochondria
Mitochondria, Liver - metabolism
Molecular Sequence Data
Oxidative Stress
Phosphorylation
Rats
Receptor, Epidermal Growth Factor - metabolism
Signal Transduction
STAT3 Transcription Factor - metabolism
Transcriptional Activation
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Summary:Studies in vascular smooth muscle cells suggest that, angiotensin II (Ang II)-mediated cellular response requires transactivation of epidermal growth factor receptor (EGF-R), and involves tyrosine phosphorylation of caveolin-1. Here we demonstrate that, exposure of WB rat liver cells to Ang II does not cause transactivation of EGF-R, but did rapidly activate p42/p44 mitogen-activated protein (MAP) kinases suggesting that it activates MAP kinases independent of EGF-R transactivation. We observed that the phospho-specific anti-caveolin-1 antibody detected a tyrosine phosphorylated, 75 kDa protein in Ang II-treated cells which we identified as glucose regulated protein-75 (GRP-75). Phosphoamino acid analysis showed that Ang II induced its phosphorylation at tyrosine, serine and threonine residues and was localized to the cytoplasm. The ability of Ang-II to induce GRP-75 phosphorylation suggests that it may play a role in the protection of cytoplasmic proteins from the damaging effect of oxidative stress known to be produced during Ang-II induced signaling.
ISSN:0003-9861
1096-0384
DOI:10.1016/j.abb.2006.10.011